Blockchains have transformed how we exchange value and build decentralized applications. Yet, despite their power, they remain mostly isolated from one another. Each ecosystem operates like an island with its own rules, programming languages and user base. The result is fragmentation: applications, protocols and assets struggle to move freely across networks. This creates friction for developers and a poor user experience.

Union solves this problem by introducing the zk interoperability Layer 1, designed as a universal settlement and liquidity layer. In practice, Union securely, quickly and cost-effectively connects different blockchains without relying on trusted middlemen.

Union’s design is built on two major innovations:

• Consensus verification, which allows validators on one chain to confirm that validators on another chain have reached agreement.

• Zero-knowledge proofs (ZKPs), which guarantee the correctness of transfers while aggregating them to improve speed and reduce costs.

But Union goes further than just building bridges — it introduces true modularity, much like LEGO blocks. Each component of the system can be developed, upgraded or replaced independently, without breaking the whole. This gives developers unmatched flexibility. They can build in any language — Solidity, Rust, Move and more — and instantly connect their blockchain or dApp to any ecosystem.

Whenever someone sends a transaction from one blockchain to another through Union, the process is both secure and efficient. On the first chain, Union creates a special proof (a ZKP) that confirms the transaction really happened. This proof is then sent to the second chain, where a smart contract or module checks it. Once verified, the transaction is finalized along with all other transactions bundled in the same proof — making the process fast and cost-effective.

Behind the scenes, Union also makes sure the validators of the first chain really agreed on the transaction by verifying their signatures inside a zero-knowledge proof. What makes this powerful is that anyone can generate these proofs using normal hardware, so the system avoids central points of control. There are no trusted middlemen, no oracles and no multi-signature groups — just pure, permissionless verification that will keep running forever, even without Union’s creators.

U token

The Union dynamic fee market is the system that makes Union work in practice. Every time something important happens on the network — like creating or checking zk proofs, updating light clients, managing routes between blockchains, or handling message passing — the Union token (U) is used. U is the “fuel” that pays for all the computation needed to keep cross-chain operations secure and reliable.

Relayers and provers, who are responsible for doing the heavy lifting in the system, get rewarded in U for their work. At the same time, users and protocols who want their transactions or cross-chain actions to be processed more quickly can pay a bit more in U to move to the front of the line. This creates a flexible market where demand is directly tied to real activity, such as proof verification or keeping chains connected.

In practice, this means U is not just a token — it’s the engine of Union. It ensures that the people running the infrastructure are incentivized to maintain and scale the network. It gives developers confidence that their apps will always have fast, reliable cross-chain settlement. And it gives users a smooth experience, with the option to prioritize critical transactions when it really matters. Over time, as more applications and chains connect through Union, the role of U naturally grows, because every new connection or proof verified increases demand for it.

Union has a total supply of 10 billion U tokens. Right now, about 1.92 billion U (around 19%) are in circulation. The full supply of 10 billion U is divided into six categories, each designed to support the long-term health of the network — from funding development, to growing the ecosystem, to maintaining Union’s core infrastructure.

Tokens distributed through the Genesis Drop are already in a pre-stake position. In the first week, the reward rate is set at 34%.

Once eU (liquid staked Union) officially launches, these tokens will automatically convert into liquid staking rewards, so holders will start earning without needing to take any extra action.

By staking U, you help secure the Union Layer 1 and its cross-chain infrastructure, while also earning rewards. Staking also gives you a voice in Union’s Crosschain Governance. Rewards are distributed fairly: if you stake 1% of all tokens, you’ll earn about 1% of the staking rewards.

Liquid staking will be available through Escher Finance, and additional vaults will also open, making it easy to stay flexible while staking.

Crosschain liquid staking

One of the hardest problems in crypto right now is liquid staking across multiple blockchains. Liquid staking lets you lock your tokens to secure a network, but still get a “receipt token” (an LST) that you can use in DeFi — for lending, trading or earning extra rewards. It makes your money work in two places at once. The problem? Today’s liquid staking tokens are stuck on the chain where they were created. For example, stETH only really works on Ethereum. If you want to use it somewhere else, you have to bridge it, swap wallets, pay fees and then bring it all back just to unstake. It’s messy, confusing and limits what you can actually do.

Union and Escher have teamed up to fix this with chain-abstracted liquid staking. That means you can stake and unstake Union tokens from any chain, with just one click. No bridges, no new wallets, no headaches.

Staking: If you’re on Ethereum, you click “stake” in your wallet. Behind the scenes, your tokens are locked on Union and you instantly get back an “LST version” of Union (eU) right in your Ethereum wallet.

Using your LST: you can now use eU anywhere — provide liquidity, lend or move it to another chain’s DeFi ecosystem.

Unstaking: When you want your original tokens back, you send in your eU from wherever you are (say Base or Berachain). Union burns it, starts the cooldown, and after 21 days, your tokens + rewards are sent straight back to the chain you’re on.

All you see is one simple action. All the complicated crosschain steps are handled automatically in the background.

This way, your staked Union tokens can live in any ecosystem, not just one. From day one, the Union LST can plug into lending markets, liquidity pools and vaults across chains. Escher will even launch vaults that can spread your tokens across multiple strategies — like staking on Union, lending on Base, and providing liquidity on Babylon — all from a single deposit.

This is the future of liquid staking: multi-chain, trustless and simple.

Introducing Auro BTC

Bitcoin is the world’s most valuable digital asset, but for most of its history it has been “idle” — sitting in wallets and not actively earning yield. Recently, a new trend called Bitcoin Liquid Staking Tokens (LSTs) has emerged, turning Bitcoin into an asset that can generate rewards while being used in DeFi. Today, this category has already grown to over $10 billion in value.

However, most existing Bitcoin LSTs come with big limitations. Many depend on centralized custody, which introduces risks if the custodian fails. Others are locked to a single blockchain or rely on unsecure bridges, making it hard to use them across different ecosystems. In addition, their yields are often unsustainable, coming from short-term incentives rather than real network activity. This has kept adoption low and limited their usefulness in DeFi.

This is where Union steps in with Auro BTC. Built natively on Union’s zero-knowledge secured interoperability layer, Auro BTC is designed to be trust-minimized, cross-chain, and composable from day one. Instead of being tied to one ecosystem, Auro BTC will be usable across Ethereum, Cosmos and beyond with verifiable custody and transparent mint-and-burn logic. This means users will be able to access real yield, cross-chain DeFi integrations and governance without relying on centralized middlemen.

By launching Auro BTC, Union is completing a key piece of the BTCfi puzzle. Since Babylon Genesis went live, Union has already moved over $40M in Bitcoin LSTs into the ecosystem, accounting for more than 99% of bridge activity. Auro BTC builds on this momentum, unlocking new utility for Bitcoin while creating fresh revenue streams to support Union’s growth.

With Auro BTC, Union is setting a new standard for how Bitcoin can be used in DeFi: natively, securely, and across any ecosystem — finally turning “digital gold” into a cross-chain yield asset.

To lead the development of Auro BTC, Union brought in Gandalf, a DeFi expert with nearly a decade of experience in yield strategy and product design. He previously helped Bedrock scale to over $700M in TVL, and he’s now shaping Auro BTC into a next-generation Bitcoin-native yield product.

In his own words:

“Union is in a unique position to lead BTCfi into its next phase. With a focus on efficiency, security, and cross-chain utility, we’ll not only solve fragmented liquidity but also open the door for mainstream adoption of yield-bearing Bitcoin.”

Union is already one of the largest Bitcoin bridges, but it does things differently:It never takes custody of your Bitcoin. Custody simply means holding someone else’s coins. Many other protocols require you to trust them to keep your Bitcoin safe. Union avoids this by using smart contracts and cryptography, so your Bitcoin always stays under your control.Bitcoin can move from its native blockchain to Ethereum, Solana, Babylon and other ecosystems safely.Auro BTC is a special type of Bitcoin token called a liquid staking token (LST). You can use Auro BTC on Ethereum, Cosmos, Babylon and more — no complicated bridging required. Auro BTC taps into Bitcoin mining through a rent-to-own system, letting holders earn rewards in Bitcoin without giving up their original coins.Auro BTC turns your Bitcoin into a DeFi-ready asset: you can earn yield, move it between chains, and use it in multiple DeFi platforms — all securely, easily, and without ever giving up custody of your Bitcoin.

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Follow us — the full guide for mainnet activity will be live as soon as the vaults are operational. This is just the beginning of Union’s cross-chain journey.